Television system



March 8, 1932. c. L. DAVIS TELEVISION SYSTEM Filed Dec. 18, 1929 3 Sheets-Sheet l IN V EN TOR. @6441440 QMQAI VM,

ATTOR EY March 8, 1 c L. DAVIS TELEVISION SYSTEM Filed DEC. 18, 1929 3 Sheets-Sheet 2 INVEN TOR.

@fjaolfm Q, Dam/La,

ATTORNEY March 8, 1932. c. L. DAVIS TELEVISION SYSTEM (5 Sheets-Sheet 5 Filed Dec. 18, 1929 INVENTOR. 'Clgf afw 9 D01.

ATTORNEY Patented Mar. 8,; 1932.

QPT-"ATE NT or-FicE CHESTER IQDAVIS, or KEOKUK; IOWLASSIGNOR T win-n1) RADIO, me, or NEW YORK,

N. Y., accuses-Arron or DELAWARE lpplication filed membe -18.1929. Serial N il 1,957;

My invention relates broadly to television systems and more particularly to a. television system femploying electrical energy of variablefrequency' for the transmission and reception of pictures. o v n One of the objects of my invention is to provide a system of television wherein the customary apertured scanning disk at. the television receiver is eliminated.

,Another' object of my invention is to provide a'system for thetransmissioniand reception of'pic'tures' or images by employing variable frequency electrical energy :to effect the scanning. V i

Still another ob I provide a television system where the receiving screen is renderedyariably luminous in accordance with the transmitted picture or image/by Virtueof potential nodes and anti- 7 nodes of electricalenergy which are caused to move'in, predetermined manner over portions ofthescreen. V p

A further 0b ect of my invention s to provide amethod for transmitting variable fre-v 2 5 .quency "energy according .to the different areas of a transmitted picture and causing electrical nodes and-antinodes at the receiver to directly and variouslyilluminate a receivingscreen in accordance withthetra'nsmitted picture. v, g 2 V y A still. further objectof my invention is to provide a televisionreceiving system wherein the longitudinal and lateral displacement of potential nodes and antinodes of electrical energy are directlyreproduced on the receivingscreen propen. 1 7 7 a I V Other and further Qb ectsof my invention reside in certain structure and arrangement of apparatus employedto carry out the-oper- 40 ationofthe system of television of my:lIl-..

vention.

i better understanding of my can beihadtfrom the specification following and from; 45.1Wl16f61l11l; t 1 I e Figure illustrates diagrammatically the electrical relationof the apparatus employed I 7 Fig.2 shows a modified arrangement of the apparatus employed in my inventio' m Figs;

' 5-6 3, 4, 5, 6 and -7 illustrate schematically'the ectof my invention is to' tion following. The several inductance sections are connected in series electrically 7 whereby the total inductance of the receiv ng he w mren e mgs and Figs. 9 and 10 illustrate schematically the method of reproducing the transmitted picture and image.

;copending applications Serial No; 299,501,.filed August 14, 1928,,ahd Serial NO.

300,979 filed August 21, 1928, describe asystem of televisionand apparatus therefor to Which the present embodiment i's'similar in many respects. The former relates particularly to the receiving screen, the latter to the system in general and the present relates to.

certain improvements ofboththe-above applications. The 'Vprincipal'feature of operation of the system oftelevision of my invention resides in the use of a directly responsive res ceivingscreen';caused to luminously'respond. I by virtue of potential nodes and antinodes 7 of electrical energy in accordance with the Variablefrequencyenergy whichin turn corresponds to the respectiveareas of the transmitted picture or-image. l y i j I L Figure 1 of the accompanying, drawings illustrates in general. the arrangement of ape paratus-employecl in the television'system of my inventionr Thereceiving screen comprises a plurality ofrluminously responsive inductance sections 1, 2, 3,4, 5, 6, 7, 8,9,10, ll and 12, arranged in the same plane and retained, in positionbymeans of asuitable framework 13. Each section of theinductance comprises an elongated glassor quartz 7. tube having a wire or coiled wire extending the length thereof. It is not essential that this wire or coil of wire be placed within the elongated tube as will appear in; the descripscreen is the sum of the inductance of the. several sections. t The receiving screen is caused tobe luminousby means of high he V. quency energy generated a by oscillator '14. Thiswill be described in detail later. Oscil l ator 14c is czuised'to develop modulated high frequency energyby virtueof modulator le. The modulation system shown is thatv or the constant current type where the sum ofthe g i 1 as shown at 17. The line wire system is shown for purposes of illustration. The line wire system is connected to the amplifier 18 which is designed to amplify variations of current;

caused by photoelectric cell 19. Photoelectric cell 19 is designed to be actuated by variations of luminous energy directed thereto by scanning disk 20. Disk 20 may be driven by a suitable motor 21.

The operation of the system may be'learned from Fig. 1 of the drawings. Oscillator 14 'iscaused to generate high frequency oscillations in the associated tank circuit 22. Load circuit 23 is coupled to circuit 22 in such man-,

ner as to effect a transfer of energy. Tank circuit 22 and load circuit 23 are preferably adjusted to near resonance and maintained in such adjustment. The load circuit 23 also includes variable condensers 24 and 25 and the luminously responsive inductance screen connected as shown. The capacity of condensers 24 and 25 is continuously changed by any suitable rotating motor 26. These condensers 24 and 25 are so connected to m0- tor 26 that the capacity is varied in opposite order. Thus while condenser 24 is increasing in capacity condenser 25 is decreasing in capacity, and vice versa. It is obvious therefore that the frequency characteristics of the load circuit do'not change. Assuming that the load circuit is adjusted to resonance with the tank circuit, standing or stationary waves will be set up in the load circuit. Since the luminously responsive inductance screen is a part of this load circuit, the standing waves will be luminously visible by virtue of the gas- I eous content in the tubular sections 1, 2 to 12.

A potential node thus established along some I section of the screen is indicated by the relative intensity of the sections and the different parts of each section. Thus where the crest of the potential is located, there will be a luminous spot. As the capacity of condensers 24 and 25 is varied it follows that the position of such luminous spot will be likewise varied.

Providing this s'potis moved along the different sections in progressive order similar to the movement of the scanning member 20 at the transmitter, the screen will reproduce the picture transmitted. The intensity of the luminous spot above referred to will be proportional tothe modulation of the high frequency energy from oscillator 14 and this in turn is proportional to the resistance of the photoelectric cell 19 or the respective light and dark areas of the transmitted picture.

It will be noted that the adjustment of condensers 24 and 25 must be accom lished in synchronism with the movement 0 the scanning member 19 at the transmitter.

Fig. 2 shows an alternative arrangement at the receiver. In this arrangement variable inductance members such as variometers 24a and 25a are substituted for variable condensers 24 and 25 shown in Fig. 1. The principle of operation is the same as above. described, the variometers being continuously adjusted in opposite order which is effective in shifting the potential node and a-ntinode established in the luminously responsive inductance screen.

' A better understanding of the s stem and method of operation can 'be had rom Figs.

3, 4, 5, 6 and 7 which showfive successive steps n the operations of scanning and reproducing. In Fig. 3' the potential crest is established near the top of the screen as indicated at X which is'manifested as a luminous spot. The scanning disk 20 employed at the transmitter is shown as of the double spiral type, the two spirals being indicated by the re erence characters a and b. Spirals a and b are adapted to scan alternate parallel lines across the picture to be transmitted, such as the, first aperture in spiral b scanning the line intermediate the lines scanned by the first and second apertures ofspiral a. As shown, 1

these alternate lines are scanned or filled in only after the lines scanned by spiral a are completed. As the first aperture in spiral a moves across the image or picture H, luminous spot X is shifted in a line to the right of the point of'origin. As shown by the dotted ar rows on the inductances 30'and 31, inductance 30 is set to a minimum value while inductance 31 is set to a maximum value. For purpose of illustration, the decrease of inductance is effected by progressively increasing the portion of the respective inductances short-circuited by the movable arms.

Fig. 4 shows another step in the operation wherein the luminous spot X has moved from line 1 near the top of the screen to line 5 progressively along lines 2, 3 and 4 although on lines 2 and 4 there is no luminosity. The dotted lines 2', 4, 6, 8, 10 and 12 indicate the inactive inductance sections, the solid lines 1, 3, 5, 7,9 and 11 indicating the active inductance sections cooperating with the movement of spirala-on the transmitting disk.

The inactive lines are rendered thus by providing the spacing of the apertures in the scanning disk equal to two times the width ofthe image H plus a small length allowing for the small inductance of the connectors between the consecutive sections of the luminous inductance. As shown in Fig. 4 the luminous spot X is on line 5 at the left thereof and the third aperture in spiral a of the transmitter scannin disk is at the" left of the transmitted image my invention is adapted to use with wired equal inductance value.

Fig.5]shows another progressive step in the operation, where spot X on the receiving -screen :has advanced one line, where the fourth aperture in spiral a hasreached the left side of image H and whereinductance 80. and inductance 31 are of substantially Fig. Gshows another step where spot X has. advanced one line,-the fifth aperture in spiral a is at the left of image H, inductance has increased in value and inductance 31 has decreaseu in value. Fig. 7 showsstill another step where spot has started acrossline 2, which line was heretofore inactive, the first aperture of spiral b has already advanced part .way

across image H and inductances 3O and 31.

have again changed in values, The active lines with spiral b are here shown as heavy lines the inactive being dotted as. before.

The only reason thatalternate lines are inactive is that there is no modulation at those particular 'tlIHG-S. The potential antinode 1S,

theoretically atv least, present along the inactil) tivelines but since there is no modulation of the energy, due totthe spacing ofthe apertures, in the transmitter scanning disk, no luminous response is 1 indicated along these lines; Due to the'connection of the inductance sections it isobvious that without such a provision, luminous spot X would first move "fromleft'to right and then from right to left. i The efiect of causing always the movement in the same direction may be pro-- duced by employingrelatively, large values of inductance ineach section proper of the screen and employing connectors between the Fig. 10 shows lines-Z), (hf ,71, j and Z by the,

other spiral. Figs. 8, 9, and 10,'talren together show the respective lines drawn across the image H correspondingto the different radii of the apertures in the two spirals of the scanning disk employed at the transmitter. The manner in which the interleaving of the lines scanned is clearly shown. 7

.E'lectric'inotors Zia-116.26 are illustrated as being energized from a like source of current to'insure synchronous operation of both the transmitter and receivingmechanism. The variable frequencyfadjustment at the receiver is accomplished in timed relation with respect to the movementof the scanning disk at the transmitter. The television system of follows: 1 V

" rivaling radio, space radio orlow frequency telephone or telegraph transmission lines.

Amongthe advantages of the, television tofore proposed is the advantage of dispensing with the usual scanning disk'atthe receiver. In the system of 111Y-1I1V11t10l1,.l3l16 receiving screen may be constructed of any system of my invention over systems heresuitablesize, such as issuitable for-home entertainment or for theatre use. A. system of 0113111 theatres. supplied with pictures from a central'studio, may be easily established in a manner much similar. to the atio-n. I r a I realize that there are many possible modifications of my chair. broadcasting stations now inoperspecification only inv details and it is'zto be understood that the embodiments, of my 1n1-' foregoing specification or by the accompany- .ing drawings but only bythe. scope of the appended claims. g r

What I claim as new and desire" to secure by Letters Patent of the United States is as 1. In theart of tiansinittin vision the combination of a luminously responsiveinductance screen, aseries circuitconnected with said inductance and resonantly'respom' sive to signaling energy for establishing nodes invention, departing from the accompanying drawings and foregoing I Vention are in no way to be restricted bythe and anti iodes of potential along saidinduci tancescreen, variableirnpedance elements disposed in said series circuit for varying'the position of said nodes and antinodes'by varying the electrical relation of said inductance screen with respect to said seriescircuit while maintaining t 1e frequency characteristics of said'series circuit andsaid inductance screen constant. i g

2. In a: television system, the combination of a luminously responsive inductance screen 7 comprising a plurality of parallel sections connected in S8IlS,'8. Il associatedenergy supply circuit and means for continuously and progressively changing theelectrical relation of said inductance screen with respect to said supply circuit while maintaining thefrequency characteristics ,of said inductancc screen and energy supply circuit constant.

3. In the art of transmitting vision, means for transmitting television signaling energy over a variable frequency rangeja luminously responsive inductance screen, an

energy supply circuit forinipressing the var- V iable frequency. signaling energy on said screen and means for continuously changing the electrical relation ofsaid inductance with respect tesaid energy supply circuit at a rate determined by the rate 0t transmissionofthe tele vision signalling energy,'-..

4. In the art of transinittingyision, means for scann ng an ob ect. and

L ergy over ;a variable frequency transniittiiig sig- V 130 a rate determined by the rate of scanning the object at the transmitter.

In the art of transmitting vision, means for transmitting television signaling energy,

a luminously responsive inductance screen, a signal receiving circuit connected n series with said screen, a continuously variable impedance disposed in said signal receiving circuit, said screen comprising a plurality of parallel sections disposed in the same plane and connected in series at the ends thereof, means for establishing potential antinodes along different parallel sections of said luminously responsive inductance screen'and means operating said continuously variable impedance at a rate determined by the rate vof transmission of the television signalingv energy,

6. In the art of transmitting vision, means for transmitting television signaling energy, a luminously responsive inductance screen, a signal receiving circuit connected in series with said screen, a continuously variable impedance disposed in said signal receiving circuit, said screen comprising a plurality of parallel sections disposed in the same plane and connected in series at the ends thereof, scanning means whereby antinodes of potential are caused to traverse parallel sections of a luminously responsive inductance screen.

7 A television system comprising means for transmitting television signaling energy over a variable frequency range, an inductance screen at a receiver, an oscillator for continuously exciting said inductance screen, a modulator for controlling the effect of said oscillator upon said inductance screen in accordance with the operation of said transmitting means, and a circuit coupling said oscillator with said inductance screen includ ing an impedance element and means for varying the effective value of said impedance at a rate determined by the rate of operation of saidtransmitting means.

8. A television system comprising means for transmitting television signaling energy over a variable frequency range, an in-' ductance screen at a receiver, an oscillator,

a circuit interconnecting said oscillator with said inductance screen whereby said oscillator operates to continuously'energize said inductance screen, said circuit including a pair of variable impedance elements connected in series with said inductance screen,

and means for periodically changing the effective values of said variable impedance elements at a rate dependent upon the rate of operation of said transmitting means.

9. A television system comprising means for transmitting television signaling energy over a variable frequency range, an inductance screen at a receiver, an oscillator, a transformer system connected with the output of said oscillator, said transformer system including primary and secondary windings, a series circuit including said secondary winding and said inductance screen, independent variable condenser elements connected in series with said inductance screen and disposed in circuit adjacent opposite ends of said secondary winding, and means for periodically varying the effective values of said condensers at a rate determined by the rate of operation of said transmitting means.

10. A television system comprising means for transmitting television signaling energy over a variable frequency range, an inductance screen at a receiver, an oscillator, a transformer having primary and secondary windings with the primary winding thereof connected with the output of said oscillator, a connection between said secondary winding and said inductance screen and separate condenser elements connected in series with said inductance screen adjacent opposite ends of said secondary winding, one of said condensers being variable for increasing the effective capacity thereof while the other of said condenser elements is variable in an opposite sense for decreasing the capacity thereof, and means for operating said condensers at a rate determined by the rate of operation of said transmitting means.

11. A television system comprising means for transmitting television signaling energy over a variable frequency range, an'inductance screen at a receiver, an oscillator, a coupling transformer including primary and secondary windings, a connection between said primary winding and the output of said oscillator, and a circuit extending between said inductance screen and said secondary winding,'said circuit including a pair of impedance elements, one of said impedance elements being connected in circuit with said inductance screen adjacent one end of said secondary windings and the other of said impedance elements being connected in said series circuit'adjacent the opposite end of said secondary winding, and means for periodically varying the effective values of said impedance elements at a rate determined by the rate of operation of said transmitting means, one of said impedance elements being effectively variable in a sense opposite to the variation of the other of said variable impedance elements.

In testimony whereof I aflix my signature.

CHESTER L. DAVIS' I iao 

